"Age-associated erectile dysfunction involves a decrease in nitric oxide availability and impaired relaxation," the authors wrote. "Decrease in erectile function associated with age was partially restored 15 to 20 minutes after injection with PnTx2-6."

Priapism -- a persistent, usually painful erection -- is a symptom of the Brazilian wandering spider's venom, but the exotic arachnid's bite can also be lethal, due to the presence of PhTx3, a potent neurotoxin, that is known to naturally occur only in the spider's venom.